Spring units for mattresses and the like

ABSTRACT

A spring unit comprises a continuous coil spring ( 5 ) contained within a sleeve ( 26 ) of strong, yet flexible, material. The unit is produced by providing a folding attachment device ( 2 ) having oppositely inclined spaced walls ( 13, 14 ) which converge from a feed end ( 3 ) to an outlet end ( 4 ), and simultaneously drawing the flexible material and the coil spring through the folding attachment device from the feed end to the outlet end with the spaced walls acting to fold the material over the coil spring and to apply a substantially uniform compressive force to the coil spring. As the material and the spring are drawn through the outlet end ( 4 ), overlapping edges of the flexible material are joined together to complete the spring unit.

[0001] This invention relates to spring units for use in mattresses,spring upholstered furniture and the like, and to a method and apparatusfor manufacturing such spring units. The invention also relates to aspring interiors comprised of a plurality of such spring units.

[0002] In our International Patent Application number WO90/01285, wehave disclosed a spring unit comprising a continuous coil springcontained within a sleeve of strong, yet flexible, material. In one ofthe arrangements described in WO90/01285 a separately formed sleeve ofcalico material is carried on a tubular former and a band of continuouscoil spring is drawn off a reel, through one end of the former and outthe other end. As the band passes through the former it draws off thesleeve from the former and entrains it around itself. In anotherarrangement described in WO90/01285 a continuous sheet of calico iscarried on a reel and the band of continuous coil spring in wound on areel. The free ends of the calico material are drawn through a V-shapedformer which serves to direct the sides of the sheet up and around theband. The sides of the calico are drawn together above the former andare stitched together.

[0003] In the former arrangement additional steps are required inseparately forming the sleeve and loading the sleeve onto the formerbefore the sleeve can entrain itself around the band. In the latterarrangement, in which the sleeve is formed simultaneously withentrainment around the band, difficulty is experienced in applying aneven compression to the continuous coil spring as the material iswrapped around it.

[0004] According to our invention a spring unit comprising a continuouscoil spring contained within a sleeve of strong, yet flexible, materialis produced by providing a folding attachment device having oppositelyinclined spaced walls which converge from a feed end to an outlet end,and simultaneously drawing the flexible material and the coil springthrough the folding attachment device from the feed end to the outletend with the spaced walls acting to fold the material over the coilspring and to apply a substantially uniform compressive force to thecoil spring whereafter as the material and the coil spring are drawnthrough the outlet end, overlapping edges of the flexible material arejoined together to form the sleeve and complete the spring unit.

[0005] The provision of the attachment device enables us to producespring units in a continuous operation, with a substantially uniformcompressive forced applied to the spring.

[0006] The inclined walls are interconnected at one pair of adjacentedges by a support plate which supports the flexible material, and thematerial is fed through a gap at the feed end of the folding attachmentdevice between the support plate and a guide bar which ensures thematerial does not buckle or crease as it is drawn through the foldingattachment device, the material being folded over the coil spring as thematerial and the coil spring exit from the outlet end of the foldingattachment device.

[0007] The overlapping edges of the material may be joined together byany convenient method. For example they may be stitched, glued, or heatwelded together. The flexible material may comprise a single layer ofthe strong yet flexible material, such as calico, which is drawn throughthe folding attachment from the reel. Alternatively the material may beof composite construction comprising inner and outer layers of fabricwith an insulator layer sandwiched therebetween. Such material may bepreformed. Preferably, however, the three layers are drawn through thefolding attachment device from separate, individual, reels.

[0008] When the overlapping edges of the flexible material are stitchedtogether following exit from the folding attachment device, a sewinghead is disposed between first and second variable speed puller feedmechanisms which act to drawn the material and the spring through thefolding attachment device and act to tension overlapping edges betweenspaced stations for joining them together by the sewing head.

[0009] Conveniently both feed mechanisms co-operate with the overlappingedges of the fabric on opposite sides of the sewing head to maintain theedges in overlapping relationship for the sewing operation and to ensurethe compressive force applied to the coil spring by the relativeinclination of the spaced walls of the folding attachment is maintained.

[0010] The folding attachment device may be positioned with the supportplate generally vertical and the inclined walls comprising upper andlower walls. This facilitates assembly since the sewing head produces aside seam, and the flexible material and a continuous coil spring aredrawn from reels rotatable about generally vertical axes.

[0011] The spring unit produced by a continuous operation is of infinitelength and is then cut to required lengths for the construction ofmattresses and the like, as otherwise described in WO90/01285.

[0012] One embodiment of our invention is illustrated in theaccompanying drawings:

[0013]FIG. 1 is a plan view of a schematic layout of apparatus formanufacturing a spring unit;

[0014]FIG. 2 is a side view of one practical form of the apparatus; and

[0015]FIG. 3 is a view on the axis of the apparatus.

[0016] The apparatus illustrated in the drawings comprising a base frame1 on which is mounted a folding attachment device 2 having a feed end 3and an outlet end 4. A reel of continuous coil spring 5, a reel 6 of theinner fabric, a reel 7 of insulator material, and a reel 8 of outerfabric are mounted on the base frame 1 for rotation about vertical axesand at locations spaced from the feed end 3 of the folding attachment.The reel 5 is positioned adjacent to the reel 6 of inner fabric. A firstinner variable speed puller feed mechanism 9 is mounted on the baseframe 1 at the outlet end 4 of the folding attachment 2 and a variablespeed chain stitch sewing head 10 is mounted on the frame 1 in a linebetween the puller feed mechanism 9 and a second outer variable speedpuller feed mechanism 11, also mounted on the frame 1.

[0017] The folding attachment device 2 comprises a metal component 12 ofchannel section comprising upper and lower planar walls 13,14 which areoppositely inclined and converge from the feed end 3 to the outlet end4. The walls are interconnected at one pair of adjacent edges by asupport plate 15, and a guide bar 16 spaced by a gap from support plate15 extends between the walls 13,14 at the feed end of the foldingattachment 2.

[0018] Each puller feed mechanism 9 and 11 comprises a pair of upper andlower toothed rollers 20,21 of which the spacing therebetween isadjustable by operation of an adjusting screw 22, and the lower roller21 of each pair is rotatably driven by an associated electric motor23,24, respectively.

[0019] In operation material from the three reels 6,7 and 8, all of awidth greater than the developed width of the continuous coil spring 5on the reel 9, is drawn into the feed end 3 of the folding attachmentdevice 2 through a space between the support plate 15 and the guide bar16, and the continuous coil 5 is also drawn into the folding attachment2 into position at which it contacts the inner fabric from the reel 6.As the two components are drawn through the folding attachment device 2by the puller mechanisms 9 and 11 the top and bottom edges of the innerand outer fabric and the insulator material fold over the top and bottomfaces of the coil spring 5 by co-operation with the upper and lowerwalls 13,14 and with the spring itself subjected to a degree ofcompression by similar co-operation with the walls 13,14. The edges ofthe fabrics are drawn down over the inner face of the coil spring 5 andare gripped between the rollers 20,21 of each puller mechanism 9,11. Thetwo mechanisms 9 and 11 acts in synchronism to draw the coil spring 5and the fabric from the reels 6,7 and 8 and through the foldingattachment device 2 to enclose the coil spring 5 within the fabric,thereby to form a continuous spring unit of infinite length.

[0020] The sewing head 10 is carried by a sewing arm which acts insynchronism with operation of the puller mechanisms 9,11 to stitch theoverlapping edges of the fabric together to form a seam 25, therebycompleting the spring unit.

[0021] The method of manufacture described above with reference to theapparatus illustrated in the drawings enables us to produced continuouslengths of spring unit in a single continuous operation in which acontinuous coil spring 5 is sheathed in a sleeve or envelope 26 ofstrong yet flexible material in which a degree of compression may beapplied to the coil spring 5 during the manufacture operation.

[0022] In a modification the stitching operation may be replaced by agluing or heat welding operation, depending upon the suitability of thematerial comprising the fabric covering or coverings.

1. A method of manufacturing a spring unit for use in mattresses, springupholstered furniture and the like, in which the spring unit comprises acontinuous coil spring (5) contained within a sleeve (26) of strong, yetflexible material (6) characterised by comprising the steps of: i)providing a folding attachment device (2) having oppositely inclinedspaced walls (13,14) which converge from a feed end (3) to an outlet end(4); ii) simultaneously drawing the flexible material (6) and the coilspring through the folding attachment device (2) from the feed end (3)of the outlet end (4) with the spaced walls (13,14) acting to fold thematerial (6) over the coil spring (5) and to apply a substantiallyuniform compressive force to the coil spring (5); and iii) joiningoverlapping edges of the flexible material (6) together at a joiningstation to form the sleeve and complete the spring unit as the material(6) and the coil spring (5) are drawn through the outlet end (4).
 2. Themethod according to claim 1, in which the inclined walls (13,14) areinterconnected at one pair of edges by a support plate (15), and a guidebar (16) spaced from the support plate (15) extends between the walls(13,14) at the feed end (3), comprising the further step of feeding thematerial (6) through the gap between the support plate (15) and theguide bar to ensure that the material does not buckle or crease as it isdrawn through the folding attachment device.
 3. Apparatus formanufacturing a spring unit for use in mattresses, spring upholsteredfurniture and the like, in which the spring unit comprises a continuouscoil spring (5) contained within a sleeve (26) of strong, yet flexiblematerial, characterised by comprising a folding attachment device (2)having oppositely inclined spaced walls (13,14) which converge from afeed end (3) of an outlet end (4), a reel of continuous coil spring, areel of flexible material, puller means (9,11) for drawing the flexiblematerial and the coil spring simultaneously through the foldingattachment device (2) from the feed end (3) to the outlet end (4) withthe spaced walls (13,14) acting to fold the material over the coilspring and to apply a substantially uniform compressive force to thecoil spring, and joining means (10) for joining together overlappingedges of the flexible material as the material and the coil spring aredrawn from the outlet end (4) of the attachment device (2) to form thesleeve and complete the spring unit.
 4. Apparatus according to claim 3,in which the inclined walls (13,14) are interconnected at one pair ofadjacent edges by a support plate (15), and the material is fed througha gap between the support plate (15) and a guide bar (16) which ensuresthat the material does not buckle or crease as it is drawn through thefolding attachment device (2), the material being folded over the coilspring as the material and the coil spring exit from the outlet end ofthe folding attachment device (2).
 5. Apparatus according to claim 3 orclaim 4, in which the joining means comprises a sewing head (10). 6.Apparatus according to claim 3 or claim 4, in which the joining meanscomprises a gluing device.
 7. Apparatus according to claim 3 or claim 4,in which the joining means comprises a heat sealing or welding device.8. Apparatus according to claim 5, in which the puller means comprisesfirst and second spaced puller feed mechanisms disposed at the outletend of the attachment device (2), and the sewing head (10) is disposedbetween the feed mechanisms (9,11), the feed mechanisms (9,11) acting todraw the material and the coil spring through the attachment device (2)and acting to tension overlapping edges between spaced stations at whichthey are joined together by the sewing head (10).
 9. Apparatus accordingto claim 8, in which both feed mechanisms (9,11) co-operate withoverlapping edges of the fabric on opposite sides of the sewing head(10) to maintain the edges in overlapping relationship for the sewingoperation and to ensure the compressive force applied to the coil springby the relative inclination of the spaced walls (13,14) of the foldingattachment is maintained.
 10. Apparatus according to claim 8 or claim 9,in which each puller feed mechanism (9,11) comprises a pair of upper andlower toothed rollers (20,21), and one roller of each pair is rotatablydriven by an associated electric motor (23,24).
 11. Apparatus accordingto claim 10, in which the spacing between the rollers (20,21) of eachpair is adjustable by operation of a respective adjusting screw (22).12. Apparatus according to any of claims 5-11, in which the foldingattachment device (2) is positioned with the support plate (15)generally vertical and the inclined walls (13,14) comprising upper andlower walls, the flexible material, and the coil spring are drawn fromreels rotatable about generally vertical axes, and the sewing head (10)is adapted to produce a side seam.
 13. A spring unit of indefinatelength for use in mattresses, spring upholstered furniture and the likemanufactured by the method of claim 1 or claim 2, and comprising acontinuous coil spring contained within a sleeve of strong, yet flexiblematerial.
 14. A spring unit of indefinate length for use in mattresses,spring upholstered furniture and the like manufactured by apparatusaccording to any one of claims 3 to 12, and comprising a continuous coilspring contained within a sleeve of strong, yet flexible material.
 15. Aspring unit according to claim 13 or claim 14, in which flexiblematerial comprises a single layer of a strong, yet flexible material.16. A spring unit according to claim 13 or claim 14, in which theflexible material is of composite construction comprising inner andouter layers of fabric with an insulator layer sandwiched therebetween.17. A spring unit according to claim 16, in which the flexible materialis pre-formed.
 18. A spring unit according to claim 16, in which thethree layers are drawn from separate, individual, reels (6,7,8).
 19. Amattress incorporating at least one spring unit assembly according toany one of claims 13 to 18.